Table component with filter and search (#600)

* Initial table component with storybook example

* Moved dependencies to package/core

* Removed dependency to @backstage/core from base package.json

* Clean up some examples and remove type from columns, replacing with property align instead

* Removed more unused stuff and added toggle for filter input

* Fixed some lint issues

* Added example with material-table

* Convert column array passed into MaterialTable Backstage component into MT column array. Allow multiple values in one cell

* Removed subheader from MT

* Nicer double value cell

* Added custom sorting to example

* Cleaned up stories a bit

* Setting field instead of customSort

* Improve styling. Still needs better theme integration

* Using more colors from theme

* Fixed typing issue

* Removed react-table implementation and cleaned up material-table implementation

* Fixed some type issues

* Fixed lint issues

plugins/explore/src/components/ExploreCard.tsx

@@ -28,7 +28,7 @@ import {
 } from '@material-ui/core';
 import { BackstageTheme } from '@backstage/theme';
 
-const useStyles = makeStyles<BackstageTheme>(theme => ({
+const useStyles = makeStyles<BackstageTheme>((theme) => ({
   card: {
     display: 'flex',
     flexDirection: 'column',

plugins/explore/src/components/ExplorePluginPage.tsx

@@ -27,7 +27,7 @@ import {
 import ExploreCard, { CardData } from './ExploreCard';
 import { BackstageTheme } from '@backstage/theme';
 
-const useStyles = makeStyles<BackstageTheme>(theme => ({
+const useStyles = makeStyles<BackstageTheme>((theme) => ({
   container: {
     display: 'grid',
     gridTemplateColumns: 'repeat(auto-fill, 296px)',